The resurfacing of the seating surface on poppet valves for internal combustion engines has typically required utilization of cumbersome and expensive machinery which effects a grinding of the seating surface by means of a grinding wheel. Such machinery is not only expensive to purchase and maintain, but it is also complex to operate. Small repair shops generally can not afford such machinery, and hence will often replace the valve due to an inability to efficiently refinish the seating surface on the old valve.
In an attempt to provide an improved tool for refacing of poppet valves, there has been suggested a valve refacing device employing a cylindrical sleevelike housing having a conical recess formed in one or both ends thereof. This valve refinishing device, as disclosed by Australian Application No. 91999/82, employs one or more carbide cutting blades which are positioned within elongated bores formed in the housing and thence project forwardly through elongated slots so that the cutting blades project outwardly from the conical surface defining the conical recess. With this device, the poppet valve is positioned so that the stem projects coaxially through a clearance opening provided in the housing, whereupon the truncated conical seating surface is positioned within the recess for engagement with the cutting blades. Relative rotation between the device and the poppet effects a cutting, and hence a refacing, of the seating surface. In one embodiment of this device, the recesses at opposite ends of the housing are of different angles to accommodate valves of two different sizes. In another embodiment, a conical shell is positionable within the conical recess, which shell captivates the blades, and the shell is held within the recess by an end cap which threadedly surrounds the housing.
While the valve refacing device of Australian Application No. 91999/82 does perform a desirable valve refacing operation, nevertheless this device does possess disadvantages. For example, the manner in which the blades are mounted on or within the housing, using either the grooved housing or the separate conical shell for confining the blades, substantially increases the complexity of the overall device and, particularly with the embodiment utilizing bores for confining the blades, makes the housing difficult and complex to machine. These arrangements also make it difficult to provide a conical recess having a minimal diameter opening at the apex end of the recess, and hence make it difficult to position the cutting blades close to the small-diameter end of the recess, whereby refacing of very small-diameter poppet valves is difficult.
Another valve refacing device has also been suggested by German Gebrauchsmuster No. G 82 30 294.4 which illustrates a device having a one-piece sleevelike housing provided with a conical recess in one end thereof, which recess has grooves extending radially along the wall thereof, and carbide cutting blades are positionable within these grooves. With this arrangement, the machining of the housing and the forming of the conical recess and blade grooves prevents the recess from being of small diameter at the apex end, and hence prevents the blades from being positioned close to the apex, whereby this device is unable to accommodate small-diameter poppet valves.
In addition, while the device of the aforementioned Australian application does disclose an embodiment having recesses at opposite ends of different angles, nevertheless this device is able to successfully accommodate only two different sizes of poppet valves, and the unit of the aforementioned German Gebrauchsmuster can accommodate only a single size (i.e., single angle) poppet valve. Thus, none of the devices discussed above have the capability of being readily adapted so as to permit utilization with poppet valves having any angle on the seating surface.
Accordingly, it is an object of this invention to provide an improved valve refacing tool of the aforementioned type, which refacing tool is structurally and functionally more advantageous than the tools described above.
In the valve refacing tool of this invention, there is provided a sleevelike housing having an enlarged cylindrical opening formed in one end thereof, which cylindrical opening terminates at its inner end in a shoulder. A sleevelike cylindrical support is removably positionable within the cylindrical opening and is securable to the housing, as by screws. This cylindrical support has a conical recess formed in the outer axial end thereof, which conical recess at its apex end communicates with a small-diameter opening which extends axially through the support and communicates with the opening which extends coaxially of the housing. This conical recess is bounded by a conical surface having a plurality of grooves formed therein and projecting radially outwardly thereof. These grooves permit carbide cutting blades to be locked in position therein. The cylindrical support is axially split so as to be defined by a plurality, preferably at least three, of arcuate sectors. This enables the central opening of the cylindrical support to be of minimal diameter, which diameter is sized so as to normally be only slightly larger than the typical valve stem and is hence a small fraction of the diameter of the conical surface at its outer or large-diameter end, whereby this permits the conical surface to be properly machined so that the apex end communicates with said opening of minimal diameter. This also enables the blade-receiving grooves to project radially to the apex end of the conical recess, and the blades themselves can be positioned close to the apex so as to readily accommodate poppet valves of small diameter. A set containing several sectored cylindrical supports is provided for association with the housing, and each one of the supports has a conical recess defined by a different included angle. The cylindrical supports can be readily interchanged to permit the valve refacing unit to be utilized with poppet valves of different angles.
The improved valve refacing tool of this invention, as briefly described above, is highly desirable since it is of a small and compact structure, it can be readily manually manipulated when refinishing of a valve seat is desired, it can be efficiently manufactured and assembled, and it provides maximum flexibility and usability due to its capability of refinishing valve seats having a wide range of diameters and angles.
Other objects and purposes of the invention will be apparent to persons familiar with tools of this general type upon reading the following specification and inspecting the accompanying drawings.